In recent years, mobile devices exemplified by smartphone, tablet terminal and PDA (Personal Digital Assistant) have been diversified in function. There are increasing lineups of mobile devices functionalized not only for telephone call and mailing, but also functionalized, as standard, for scheduling, camera, and various sensors. In business use of mobile device, the mobile devices may be provided by an organization such as company to the employees, but it has widely been conventionalized that the mobile devices personally owned by the employees are put into business use. Use of the personally-owned mobile devices not only for private purpose but also for business purpose is referred to as BYOD (Bring Your Own Device).
On the other hand, leakage of information through the mobile devices is becoming a problem. Examples of the problem include information leakage of confidential documents or facilities in the form of image acquired by the camera function, storage of files attached to business mails into a cloud service for personal use, and transfer of data of an address book for business use. In particular, standard installation of the camera function on the mobile devices has accelerated the risk of such information leakage. There has therefore been proposed inventions to prevent information leakage using the camera function.
According to a system of Patent Literature 1, a mobile device, with its camera device powered on, sends an imaging enable signal from the mobile device to a server at predetermined time intervals, and the server detects the location of the mobile device based on the signal. When the server receives the imaging enable signal from the mobile device which resides in an imaging prohibition zone, the server activates a secret photographing prevention device of the mobile device. The secret photographing prevention device is a notification means using alarm or sound, a lock-and-key device, a means for reporting to a security guard, and so forth.
A system described in Patent Literature 2 is an operation control system which opens an entrance-exit gate, upon reception of a signal indicating that the camera function of the mobile device has been disabled.